Search PubMed⌕ Search

Biomedical subjects

C H Smith

Publications and source records attributed to C H Smith.

At least 55 records · Page 3Linked to original sources
PubMed1998

Preliminary results of bedside inferior vena cava filter placement: safe and cost-effective.

The use of inferior vena cava filters (IVCFs) is increasing in patients at high risk for venous thromboembolism; however, there is considerable controversy related to their cost. We inserted eight percutaneous IVCFs at the bedside. The hospital charges for bedside IVCF insertion were substantially lower compared with those for IVCF insertion performed in the Radiology Department or operating room. There was one death (unrelated to the procedure) and one asymptomatic caval occlusion believed to be caused by thrombus trapping. Bedside IVCF insertion is safe and cost-effective in selected patients. This practice averts the potential complications associated with transporting critically ill patients.

Adult↗
PubMed1998

HPLC detection of fetal blood in meconium: improved sensitivity compared with qualitative methods.

We describe an HPLC-based method for the detection and quantification of fetal hemoglobin in stools of newborns. The new procedure is an alternative to the classic qualitative test for adult hemoglobin in meconium based on the differential stability of hemoglobin species in dilute base (Apt test). The HPLC method, based on a commercial device for hemoglobin characterization (Bio-Rad Variant), readily separates fetal and adult hemoglobin from non-hemoglobin components of meconium. To validate the method, blood and meconium were mixed in various proportions and then prepared for analysis with extraction in saline. The HPLC method accurately identified hemoglobin species even when the blood constituted only 5 mL per 100 g of the meconium specimen, and nearly quantitative recovery of hemoglobin was obtained at a blood content of 20 mL per 100 g of the meconium. Analysis time was 6.5 min, and preparation of sample was simple. HPLC detection of fetal blood in stools or other specimens markedly improves detection/characterization of blood in meconium.

Chromatography, High Pressure Liquid↗
PubMed1997

Visual loss as a complication of spine surgery. A review of 37 cases.

STUDY DESIGN: Thirty-seven patients who experienced visual loss after spine surgery were identified through a survey of the members of the Scoliosis Research Society and a review of the recent literature. OBJECTIVES: Records were reviewed in an attempt to identify preoperative and intraoperative risk factors and to assess the likelihood of recovery. SUMMARY OF BACKGROUND DATA: Postoperative blindness after spine surgery has been documented in case reports or small series. The authors report the largest group of such cases to date and the first to allow conclusions regarding risk and prognosis. METHODS: Letters were sent to members of the Scoliosis Research Society requesting copies of medical records concerning patients who experienced postoperative visual deficits after spine surgery. An additional 10 well-documented recent cases were identified from published reports. RESULTS: Patients with visual loss had a mean age of 46.5 years. Surgery included instrumented posterior fusion in 92% of the cases, with an average operative time of 410 minutes and blood loss of 3500 mL. Most cases had significant intraoperative hypotension, with a mean drop in systolic blood pressure from 130 to 77 mm Hg. However, comparison with a matched group of patients with no visual symptoms showed no differences in the hematocrit or blood pressure values. Visual loss occurred because of ischemic optic neuropathy, retinal artery occlusion, or cerebral ischemia. Eleven cases were bilateral, and 15 patients had complete blindness in at least one eye. Most deficits were permanent. CONCLUSIONS: The authors conclude that blindness after spine surgery is more common than has been recognized previously. Most cases are associated with complex instrumented fusions.

Blindness↗
PubMed1997

Oral sensory discrimination of fluid viscosity.

This study was designed to investigate the ability of normal young adult volunteers to sensorially identify Newtonian fluids of specified viscosities. Twenty subjects, 10 men and 10 women between the ages of 18 and 29 years participated. Seven stimuli, consisting of combinations of corn syrup and water, with viscosities ranging from 2 to 2,240 centipoise (cP) were prepared and characterized using a coaxial rotational viscometer. Subjects were presented with two anchor stimuli representing the extremes of the range of viscosities as a basis from which the experimental stimuli were judged. The seven experimental stimuli were randomly presented to each subject 10 times. The accuracy with which the subjects identified the viscosity of the fluid was significant at p < 0.01. The pattern of response was not significantly different across subjects nor gender. There were no differences in performance throughout the duration of the study. The repeat presentation of the anchor points did not significantly affect performance. Further research on oral perception of viscosity, and the processes that mediate changes in swallow physiology resulting from changes in viscosity is required.

Adult↗
PubMed1997

Identification of two leucine-sensitive lysine transport activities in human placental basal membrane.

The recent demonstration of multiple high-affinity leucine-sensitive cationic transport systems prompted this investigation of their role in lysine uptake in basal cell membrane. Transport of lysine by basal membrane was saturable at both 22 and 37 degrees C and linear in time to 1 min and 30 sec, respectively. At 22 degrees C, at least two systems were active. The portion of uptake inhibited by the sulphydryl binding reagent N-ethylmaleimide (NEM) but not by leucine in the absence of sodium had a high K(m) and high Vmax and was attributed to system y+. NEM-insensitive uptake was fitted by a one-system model with K(m) (+/- s.e.) of 4 +/- 1 microM and a Vmax of 0.9 +/- 0.1 pmol/mg protein/min. This component was completely inhibited by leucine in the absence of sodium but not by glutamine in the presence of sodium. Therefore, it was attributed to system bo,+. At 37 degrees C, at least three systems were active. For essentially the same reasons as above the NEM inhibitable uptake was attributed to system y+. NEM-insensitive uptake was fitted by a one-system model with K(m) of 26 +/- 7 microM and Vmax of 11.1 +/- 2.8 pmol/mg protein/30 sec. Inhibition studies, however, indicated its heterogeneity. NEM-insensitive saturable uptake was only partially inhibited by either leucine in the absence of sodium (system bo,+) or by glutamine in the presence of sodium (system y+L). It is concluded that the NEM-insensitive portion of lysine uptake at 37 degrees C represents activity of both system bo,+ and the temperature-sensitive system y+L. As a previous investigation indicates, only one of these (system y+L) is present in the more specialized microvillous membrane. The demonstration of functional differences in the high affinity leucine transporters of basal and microvillous membrane in this and our previous investigations suggest that the two membranes possess different transport or modifier proteins.

Amino Acid Transport Systems, Basic↗
PubMed1997

A survey for torovirus in New Zealand cats with protruding nictitating membranes.

Faecal samples from 51 cats were examined by negative stain electron microscopy to investigate a possible association between the syndrome of bilateral protrusion of the nictitating membranes and torovirus infection. Although toroviruses were not observed in any sample, other viruses or virus-like particles were observed in faeces from one of 15 cats with the syndrome, six of 21 cats which had experienced prior episodes of the syndrome and four of 15 healthy control cats. The findings of this study do not support the hypothesis that the syndrome is associated with torovirus infection.

Journal Article↗
PubMed1997

Spatial polarization of insulin-like growth factor receptors on the human syncytiotrophoblast.

The expression of IGF receptors on the maternal-facing, microvillous membrane (MVM) surface and the fetal-facing, basal membrane (BM) surface of the syncytiotrophoblast was studied using standard ligand binding assays, covalent cross-linking techniques, and immunoblot analysis. Scatchard analysis of [125I]IGF-I and -II binding revealed the presence of both high and low affinity binding sites associated with each membrane preparation that did not clearly distinguish between the two membrane preparations. Cross-linking analysis, however, demonstrated type I and type II IGF receptors associated primarily with MVM, suggesting that nonreceptor binding sites may contribute to total membrane binding. Ligand blot analysis revealed that BM are uniquely associated with 29- and 24-kD IGF binding proteins (IGFBPs). [125I]QAYL-IGF-I, having reduced affinity for IGFBPs, was therefore used to study receptor-specific binding. Approximately 5-fold more type I IGF receptors were shown to be associated with MVM than BM by Scatchard and cross-linking analyses. This was confirmed by immunoblot analysis. By contrast, immunoblot analysis revealed approximately 50-100% more type II IGF receptor protein associated with BM, whereas cross-linking to [125I]IGF-II revealed a MVM predominance. In the presence of 5 mM mannose 6-phosphate, however, a substantial increase in [125I]IGF-II cross-linked to the type II IGF receptor was observed in BM but not MVM consistent with immunoblot analysis. These data demonstrate that type 1 and unoccupied type II IGF receptors are expressed primarily on the maternal-facing. MVM surface of the syncytiotrophoblast.

Embryonic and Fetal Development↗
PubMed1997

Extraction of glyceric and glycolic acids from urine with tetrahydrofuran: utility in detection of primary hyperoxaluria.

Primary hyperoxaluria (PH) is an autosomal recessive metabolic abnormality characterized by excessive oxalate excretion leading to nephrocalcinosis and progressive renal dysfunction. Type I primary hyperoxaluria (PH I) results from a deficiency of alanine:glyoxylate aminotransferase, whereas type II disease has been traced to a deficiency of D-glycerate dehydrogenase. The two syndromes are often distinguished on the basis of organic acids that are coexcreted with oxalate: glycolate and L-glycerate in type I and type II disease, respectively. Routine organic acid analysis with diethyl ether extraction followed by gas chromatographic analysis failed to detect normal and increased concentrations of these diagnostic metabolites. Subsequent extraction of urine with tetrahydrofuran (THF), however, extracted 75% of added glycerate, 42% of added glycolate, and 75% of added ethylphosphonic acid (internal calibrator). THF extraction was analytically sensitive enough to allow determination of normal excretion of glycolate (14-72 micrograms/mg creatinine) and glycerate (0-5 years, 12-177 micrograms/mg creatinine and > 5 years, 19-115 micrograms/mg creatinine). Four of five patients with PH I and both patients with type II disease were correctly identified. Thus, THF extraction is a convenient adjunct to routine organic acid analysis and facilitates the detection of PH.

Adolescent↗
PubMed1997

Measurement of plasma ibuprofen by gas chromatography-mass spectrometry.

A gas-chromatography-mass spectrometry (GC-MS) method for the determination of plasma ibuprofen was developed. Plasma samples from cystic fibrosis (CF) patients receiving high-dose ibuprofen therapy were analyzed by GC-MS and the result compared to analysis by high-performance liquid chromatography (reference method). Analysis of ibuprofen was sensitive to at least 5 mg/L, and the method was linear to 200 mg/L. Within-run variations of plasma samples were 4.6% (131.7 +/- 6.0 mg/L) and 5.4% (44.4 +/- 2.4 mg/L), respectively. The between-run variation was 9.3% (45.4 +/- 4.2 mg/L) and 7.4% (88.0 +/- 6.5 mg/L). This method is suited for routine clinical use for the monitoring of plasma ibuprofen levels in treatment of CF. It may be particularly applicable in pediatric laboratories, which are likely to possess GC-MS capability.

Chromatography, High Pressure Liquid↗
PubMed1996

Speciation of arsenic oxides using laser desorption/ionization time-of-flight mass spectrometry.

Positive and negative ion mass spectra of arsenic trioxide (As2O3) and arsenic pentaoxide (As2O5) have been obtained by single-step laser desorption/ionization time-of-flight mass spectrometry. Pulsed UV radiation at 266 nm was used for the simultaneous desorption and ionization of the solid sample. High-mass cluster ions that are unique to the oxidation state of each oxide sample appear in the negative ion mass spectra. The As2O3 produces As3O5-, while the As2O5 yields As3O8-. The formation of unique negative cluster ions presents the capability for arsenic oxidation state speciation by laser desorption/ionization mass spectrometry. The ability of time-of-flight mass spectrometry to examine the relative amounts of each arsenic oxide present in a series of mixtures is discussed. Application of our speciation technique to a model incinerator sample is demonstrated.

Arsenic Trioxide↗
PubMed1996

Laser desorption/ionization time-of-flight mass spectrometry of nitrated polycyclic aromatic hydrocarbons.

Mass spectra of four nitrated polycyclic aromatic hydrocarbons (nitro-PAHs), 9-nitroanthracene, 1-nitropyrene, 2-nitro-9-fluorenone, and 2-nitrofluorene, have been investigated using single-step laser desorption/ionization time-of-flight mass spectrometry. Pulsed UV radiation at 266 or 213 nm was used for desorption and ionization of solid samples deposited on an aluminum probe. The positive molecular ion which was observed for each nitro-PAH was of greater relative intensity when 213 nm radiation was used. A strong [M - NO]+ peak was observed in all spectra, and an intense NO+ signal accompanied the [M - NO]+ signal when 213 nm was used but was only weakly present when 266 nm was used. Comparison of the various spectra suggests that nitro-PAHs undergo an excited state nitro-nitrite rearrangement, followed by loss of NO. Multiphoton ionization of the NO fragment appears to be the principal route of formation of NO+ during laser desorption/ionization when 213 nm radiation is used. The presence of the carbonyl group in 2-nitro-9-fluorenone leads to unique and prominent fragments involving losses of CO from the carbonyl bridge.

Air Pollutants↗
PubMed1996

Weak extremely-low-frequency magnetic field-induced regeneration anomalies in the planarian Dugesia tigrina.

We recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. We report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 microT. These anomalies often culminate in the complete disaggregation of the organism. Similar to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 microV/m. The addition of either 51.1 or 78.4 microT DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas our previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling. These results together with those reported previously point to two distinct physiological effects produced in regenerating planaria by exposure to weak extremely-low-frequency (ELF) magnetic fields. They further suggest that the planarian, which has recently been identified elsewhere as an excellent system for use in teratogenic investigations involving chemical teratogens, might be used similarly in teratogenic investigations involving ELF magnetic fields.

Abnormalities, Radiation-Induced↗
PubMed1996

Functional expression of the plasma membrane serotonin transporter but not the vesicular monoamine transporter in human placental trophoblasts and choriocarcinoma cells.

We investigated the functional expression of the plasma membrane serotonin transporter and the vesicular monoamine transporter in choriocarcinoma cells and normal trophoblasts. The RBL 2H3 cells, a rat basophilic leukaemia cell line, which express both transporters were used for comparison. The choriocarcinoma cells JAr and BeWo were found to possess the plasma membrane serotonin transporter as assessed by the presence of serotonin transport activity in intact cells that was Na(+)-dependent and was sensitive to inhibition by tricyclic and non-tricyclic antidepressants. The activity of the vesicular monoamine transporter in these cells was determined by measuring serotonin transport in digitonin-permeabilized cells. The transport in permeabilized cells was very slow, was not stimulated by ATP and was insensitive to inhibition by reserpine. Under similar conditions, the vesicular monoamine transporter activity was demonstrable in RBL cells, which was stimulated by ATP and was inhibitable by reserpine, bafilomycin A1 (an inhibitor of the V-type H(+)-pump) and carbonyl cyanide p-trifluoromethoxy phenylhydrazone (a protonophore which dissipates transmembrane H+ gradients). In corroboration with these findings, mRNA transcripts hybridizable to the vesicular monoamine transporter cDNA probe were detectable in RBL cells but not in JAr choriocarcinoma cells. Similarly, there was no evidence for the expression of the vesicular monoamine transporter as assessed by Northern blot analysis in normal trophoblasts which were maintained in culture to differentiate to form multinucleated syncytial cells. It is concluded that the trophoblasts and choriocarcinoma cells express the plasma membrane serotonin transporter but not the vesicular monoamine transporter.

Adenosine Triphosphate↗
PubMed1996

Mesenteric vasculitis associated with Sézary syndrome.

A 71 year old lady with Sézary syndrome presented with chronic diarrhoea and cramping abdominal pains. A small bowel meal x ray examination showed two mid-ileal strictures. At laparotomy the small intestine was found to be sub-acutely obstructed and resection of a 15 cm ileal stricture and stricturoplasty of a second, 10 cm stricture were performed. Histological examination of the stricture revealed a mesenteric vasculitis with secondary ischaemic changes in the small bowel wall. Mesenteric vasculitis causing small bowel stricture may be associated with Sézary syndrome.

Aged↗
PubMed1996

Radioimmunoassay of leptin in human plasma.

Recent studies suggest that leptin, the ob gene product absent in ob/ob mice, is a negative regulator of adiposity. We developed an RIA to measure human leptin in plasma or serum. The minimum detectable concentration by the assay is 0.5 microg/L leptin and the limit of linearity is 100 microg/L. Recovery of leptin added to serum was 99-104% over by the linear range of the assay. The RIA agreed reasonably well with rough quantification by Western blot (RIA = 0.90 blot + 3.7 microg/L, Sy/x = 10.9 microg/L). CVs within- and between-run ranged from 3.4% to 8.3% and from 3.6% to 6.2%, respectively. Variation in plasma leptin concentrations in specimens collected on consecutive mornings was large (CVs of 10.9% and 22.5%). After an overnight fast, leptin concentrations were similar to those 1-2 h after 1-2 meals. Plasma leptin concentrations in specimens from 83 lean and obese adults correlated directly with body mass index (BMI; kg/m2): r = 0.72, P <0.001. Correlations were significantly improved by separating results by gender (men r = 0.84, women r = 0.87; p <0.001). The increase in leptin concentrations with increasing BMI was greater in women than in men (slope 2.53 vs 0.97 microg/L per unit BMI, respectively). Leptin concentrations determined in lean subjects (BMI between 18 and 25) were higher in women (7.36 +/- 3.73 microg/L) than in men (3.84 +/- 1.79 microg/L) (P <0.001). Plasma leptin varied little with age and no significant difference was observed between whites and blacks. We conclude that: (a) plasma leptin concentrations are accurately and precisely measured by this new RIA; (b) leptin concentrations vary little due to short-term fasting, age, or race; but (c) plasma leptin concentrations are gender specific.

Adolescent↗
PubMed1996

Eosinophil infiltration into human skin is antigen-dependent in the late-phase reaction.

Eosinophils play a critical role in late-phase reaction allergic inflammatory responses, although the factors responsible for selective tissue eosinophilia are currently ill-defined. To determine whether recruitment of eosinophils is allergen-specific, or a feature of inflammation in allergic individuals, we have examined cutaneous cell infiltrates and endothelial cell adhesion molecule expression in atopic subjects 6 h (n = 8) and 24 h (n = 7) following ultraviolet-B (UVB) irradiation, or intradermal injection of late-phase reaction allergens or diluent control, using standard immunohistochemical techniques. The numbers of eosinophils were increased significantly, when compared to controls, at both 6 h (P < 0.01) and 24 h (P < 0.05), following intradermal allergen challenge, whereas no significant increase in eosinophils was observed following UVB irradiation. UVB and allergen both induced significant increases in neutrophils, monocytes and T cells at 24 h compared to control sites. An increased expression of endothelial cell adhesion molecules, E-selectin and intercellular adhesion molecule-1 (ICAM-1), was observed in both models of inflammation. Vascular cell adhesion molecule-1 (VCAM-1) was induced weakly on some biopsies following allergen, and not at all following UVB. These data indicate that eosinophil infiltration in susceptible individuals is a specific property of allergen. Although this study would support the postulated role of VCAM-1 in selective eosinophil recruitment, given its variable and weak expression, additional factors are likely to be involved.

Allergens↗